Methods and apparatus for controlling photoresist line width roughness with enhanced electron spin control

ABSTRACT

The present disclosure provides methods and an apparatus for controlling and modifying line width roughness (LWR) of a photoresist layer with enhanced electron spinning control. In one embodiment, an apparatus for controlling a line width roughness of a photoresist layer disposed on a substrate includes a processing chamber having a chamber body having a top wall, side wall and a bottom wall defining an interior processing region, a support pedestal disposed in the interior processing region of the processing chamber, and a plasma generator source disposed in the processing chamber operable to provide predominantly an electron beam source to the interior processing region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/455,753, entitled “METHODS AND APPARATUS FOR CONTROLLINGPHOTORESIST LINE WIDTH ROUGHNESS WITH ENHANCED ELECTRON SPIN CONTROL”,filed Apr. 25, 2012, which claims benefit of U.S. ProvisionalApplication Ser. No. 61/497,370 filed on Jun. 15, 2011, which are hereinincorporated by references.

BACKGROUND

Field

The present disclosure generally relates to methods and apparatus forcontrolling photoresist line width roughness and, more specifically, tomethods and apparatus for controlling photoresist line width roughnesswith enhanced electron spin control in semiconductor processingtechnologies.

Description

Integrated circuits have evolved into complex devices that can includemillions of components (e.g., transistors, capacitors and resistors) ona single chip. The evolution of chip designs continually requires fastercircuitry and greater circuit density. The demands for greater circuitdensity necessitate a reduction in the dimensions of the integratedcircuit components.

As the dimensions of the integrated circuit components are reduced (e.g.to sub-micron dimensions), more elements are required to be put in agiven area of a semiconductor integrated circuit. Accordingly,lithography process has become more and more challenging to transfereven smaller features onto a substrate precisely and accurately withoutdamage. In order to transfer precise and accurate features onto asubstrate, a desired high resolution lithography process requires havinga suitable light source that may provide a radiation at a desiredwavelength range for exposure. Furthermore, the lithography processrequires transferring features onto a photoresist layer with minimumphotoresist line width roughness (LWR). After all, a defect-freephotomask is required to transfer desired features onto the photoresistlayer. Recently, an extreme ultraviolet (EUV) radiation source has beenutilized to provide short exposure wavelengths so as to provide afurther reduced minimum printable size on a substrate. However, at suchsmall dimensions, the roughness of the edges of a photoresist layer hasbecome harder and harder to control.

FIG. 1 depicts an exemplary top isometric sectional view of a substrate100 having a patterned photoresist layer 104 disposed on a targetmaterial 102 to be etched. Openings 106 are defined between thepatterned photoresist layer 104 readily to expose the underlying targetmaterial 102 for etching to transfer features onto the target material102. However, inaccurate control or low resolution of the lithographyexposure process may cause in poor critical dimension control in thephotoresist layer 104, thereby resulting in unacceptable line widthroughness (LWR) 108. Large line width roughness (LWR) 108 of thephotoresist layer 104 may result in inaccurate feature transfer to thetarget material 102, thus, eventually leading to device failure andyield loss.

Therefore, there is a need for a method and an apparatus to control andminimize line width roughness (LWR) so as to obtain a patternedphotoresist layer with desired critical dimensions.

SUMMARY

The present disclosure provides methods and an apparatus for controllingand modifying line width roughness (LWR) of a photoresist layer withenhanced electron spin control. In one embodiment, an apparatus forcontrolling a line width roughness of a photoresist layer disposed on asubstrate includes a processing chamber having a chamber body having atop wall, side wall and a bottom wall defining an interior processingregion, a support pedestal disposed in the interior processing region ofthe processing chamber, and a plasma generator source disposed in theprocessing chamber operable to provide predominantly an electron beamsource to the interior processing region.

In another embodiment, a method for controlling line width roughness ofa photoresist layer disposed on a substrate includes providing asubstrate having a patterned photoresist layer disposed thereon into aprocessing chamber, supplying a gas mixture into the processing chamber,generating an electron beam from the gas mixture having electrons movingin a circular mode from the gas mixture, generating a magnetic field toenhance spinning of electrons in the electron beam moving in thecircular mode to a substrate surface, and trimming an edge profile ofthe patterned photoresist layer disposed on the substrate surface withthe enhanced electrons.

In yet another embodiment, a method for controlling line width roughnessof a photoresist layer disposed on a substrate includes supplying a gasmixture into a processing chamber having a substrate disposed therein,wherein the substrate has a patterned photoresist layer disposedthereon, generating an electron beam in the processing chamber from thegas mixture supplied in the processing chamber, applying a voltage to ashield plate disposed in the processing chamber to filter ions from theelectron beam, directing the electron beam through a control plate,applying a DC or AC power to a group of one or more electromagneticcoils disposed around an outer circumference of the processing chamberto generate a magnetic field, enhancing movement of the electron beam incircular mode by passing through the filtered electron beam in themagnetic field and rotating the electron beam to trim an edge profile ofthe patterned photoresist layer using the electron beam.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure are attained and can be understood in detail, a moreparticular description of the disclosure, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings.

FIG. 1 depicts a top isometric sectional view of an exemplary structureof a patterned photoresist layer disposed on a substrate conventionallyin the art;

FIG. 2A depicts a schematic cross-sectional view of an inductivelycoupled plasma (ICP) reactor with enhanced electron spin control usedaccording to one embodiment of the disclosure;

FIG. 2B depicts an electron trajectory diagram according to oneembodiment of the disclosure;

FIG. 3 depicts an electron trajectory diagram passing through a beamcontrol plate disposed in the ICP plasma reactor depicted in FIG. 2;

FIG. 4 depicts a flow diagram of one embodiment of performing aphotoresist line width roughness control process according to oneembodiment of the present disclosure;

FIG. 5 depicts a top view of electron trajectories traveled adjacent toa photoresist layer according to one embodiment of the presentdisclosure; and

FIG. 6 depicts a profile of a line width roughness of a photoresistlayer disposed on a substrate according to one embodiment of thedisclosure.

FIG. 7 depicts another embodiment of a control plate and/or a shieldplate;

FIG. 8 depicts yet another embodiment of a control plate and/or a shieldplate; and

FIG. 9 depicts still another embodiment of a control plate and/or ashield plate.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

It is to be noted, however, that the appended drawings illustrate onlyexemplary embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

DETAILED DESCRIPTION

Embodiments of the present disclosure include methods and apparatus forcontrolling line width roughness (LWR) of a photoresist layer disposedon a substrate. The line width roughness (LWR) of a photoresist layermay be controlled by performing an ICP plasma process with enhancedelectron spin control on a photoresist layer after anexposure/development process. The ICP plasma process is performed toprovide a chemical and electron grinding process in a nanometer scalewith enhanced electron spin control to smooth the edge of thephotoresist layer pattern with sufficient electron spin momentum,thereby providing a smooth pattern edge of the photoresist layer withminimum pattern edge roughness for subsequent etching processes. The ICPplasma process with enhanced electron spin control may also used to etcha target material disposed underneath the photoresist layer on thesubstrate subsequent to the photoresist line edge roughness minimizationprocess.

FIG. 2A depicts a schematic, cross-sectional diagram of one embodimentof an ICP plasma reactor 200 suitable for performing plasma process withenhanced electron spin control according to the present disclosure. Onesuch etch reactor that may be adapted for performing the disclosure maybe available from Applied Materials, Inc., of Santa Clara, Calif. It iscontemplated that other suitable plasma process chamber may also beemployed herein, including those from other manufacturers.

The plasma reactor 200 includes a processing chamber 248 having achamber body 210. The processing chamber 248 is a high vacuum vesselhaving a vacuum pump 228 coupled thereto. The chamber body 210 of theprocessing chamber 248 includes a top wall 222, a sidewall 224 and abottom wall 226 defining an interior processing region 212 therein. Thetemperature of the sidewall 224 is controlled using liquid-containingconduits (not shown) that are located in and/or around the sidewall 224.The bottom wall 226 is connected to an electrical ground 230.

The processing chamber 248 includes a support pedestal 214. The supportpedestal 214 extends through the bottom wall 226 of the processingchamber 248 into the interior processing region 212. The supportpedestal 214 may receive a substrate 250 to be disposed thereon forprocessing.

A plasma generator source 202 is attached to top of the chamber body 210configured to supply electrons to the interior processing region 212. Aplurality of coils 208 may be disposed around the plasma generatorsource 202 to insist creating inductively coupled plasma from the plasmagenerator source 202.

Processing gases may be introduced to the interior processing region 212from a gas source 206 coupled to the processing chamber 248. Theprocessing gases from the gas source 206 are supplied to the interiorprocessing region 212 through the plasma generator source 202. Currentis applied to the coil 208 from a power source which creates theelectric field that dissociates the gas. The processing gasesdissociated by the coils 208 forms an electron beam 249 to be deliveredto the interior processing region 212 for processing.

A group of one or more coil segments or electromagnetic coils 221 (shownas 221A and 221B) are disposed around an outer circumference of a lowerportion 211 of the chamber body 210 adjacent to the interior processingregion 212. Power to the coil segment(s) or magnets 221 is controlled bya DC power source or a low-frequency AC power source (not shown). Theelectromagnetic coils 221 generate the magnetic field in a directionperpendicular to the substrate surface where the electron beam 249 isintroduced into the processing chamber 248. As the electrons from theelectron beam 249 may not have sufficient momentum to reach down to theinterior processing region 212 further down to an upper surface 253 ofthe substrate 250, the group of the coil segments or electromagneticcoils 221 may be disposed at the lower portion of the chamber body 210(e.g., close to the interior processing region 212) to enhance spinningand/or whirling of the electrons down to the upper surface 253 of thesubstrate 250. The interaction between the electric field and magneticfield generated from the group of the coil segments or electromagneticcoils 221 causes the electron beam 249 having enhanced electron spinningand/or whirling momentum to down to the surface of the substrate 250. Itis noted that other magnetic field source capable of generatingsufficient magnetic field strength to promote electron beam (e-beam)source may also be used.

In one embodiment, a shield plate 262 is disposed in the processingchamber 248 above the support pedestal 214. The shield plate 262 is asubstantially flat plate comprising a plurality of apertures 270. Theshield plate 262 may be made of a variety of materials compatible withprocess needs, comprising one or more apertures 270 that define desiredopen areas in the shield plate 262. In one embodiment, the shield plate262 may be fabricated from a material selected from a group consistingof copper or copper coated ceramics. The open areas of the shield plate262 (i.e., the size and density of the apertures 270) assist incontrolling the amount of ions/electrons which mainly consist ofelectron beam and small amount of ions formed from the plasma generatorsource 202 to the interior processing region 212 above the upper surface253 of the substrate 250. Accordingly, the shield plate 262 acts as anion/electron filter (or electron controller) that controls the electrondensity and/or ion density in volume passing through the shield plate262 to the upper surface 253 of the substrate 250.

During processing, a voltage from a power source 260 may be applied tothe shield plate 262. The voltage potential applied on the shield plate262 may attract ions from the plasma, thereby efficiently filtering theions from the plasma, while allowing only neutral species, such asradicals and electrons, to pass through the apertures 270 of the shieldplate 262. Thus, by reducing/filtering the amount of ions through theshield plate 262, grinding or smoothing of the structures formed on thesubstrate by neutral species, radicals, or electrons, i.e., mildreactive species, can be processed in a more controlled manner.Therefore, the mild reactive species may reduce likelihood of undesirederosion sputter, or overly aggressive ion bombardment that may cause tothe substrate surface, thereby resulting in precise smoothingperformance and critical dimension uniformity. The voltage applied tothe shield plate 262 may be supplied at a range sufficient to attract orretain ions from the plasma, thereby repelling the neutral species,radicals, or electrons from the ions generated in the plasma. Thus, themild reactive species are extracted from the plasma by the shield plate262. In one embodiment, the voltage is applied to the shield plate 262from the power source 260 between about 50 Volts DC and about 200 VoltsDC. In another embodiment, the mild reactive species are extracted fromthe plasma by the shield plate 262 are predominantly electrons.

A control plate 264 is disposed below the shield plate 262 and above thesupport pedestal 214. The control plate 264 has a plurality of apertures268 that allows the neutral species, radicals, or electrons filteredthrough the shield plate 262 to pass therethrough into the interiorprocessing region 212. The control plate 264 is positioned in aspaced-apart relationship with the shield plate 262 at a predetermineddistance 266. In another embodiment, the control plate 264 is to attachto the shield plate 262 with minimum space in between. In oneembodiment, the distance 266 between the shield plate 262 and thecontrol plate 264 is less than about 20 mm.

A voltage from a power source 251 may be applied to the control plate264, so as to create a voltage potential (e.g., an electrical potential)that interacts with the magnetic field generated from the group of thecoil segments or electromagnetic coils 221 (shown as 221A and 221B). Theelectrical potential generated by the control plate 264 along with themagnetic field generated by the group of the coil segments orelectromagnetic coils 221 assist and enhance maintaining sufficientmomentum and energy to keep the neutral species, radicals, or electronsspinning down to the upper surface 253 of the substrate 250.Furthermore, the neutral species, radicals, or electrons passing throughthe apertures 268 of the control plate 264 may be directed in apredetermined path, thereby confining the trajectory of the neutralspecies, radicals, or electrons in a predetermined path to reach to adesired area on the upper surface 253 of the substrate 250. When passingthrough the control plate 264, the magnified field may cause the neutralspecies, radicals, or electrons passing through to keep moving in acircular mode and spinning toward to the upper surface 253 of thesubstrate 250. The spin electrons have to grid the structures withsufficient momentum to bottoms of the structures formed on the uppersurface 253 of the substrate 250.

In one embodiment, the control plate 264 may have different materials ordifferent characteristics. The control plate 264 may comprise more thanone zone or segments having at least one characteristic that isdifferent from each other. For example, the control plate 264 may have anumber of zones with different configurations including variousgeometries (e.g., sizes, shapes and open areas) and the zones may bemade of the same or different materials, or be adapted to have differentpotential bias or different powers. By providing combinations of zoneconfigurations, materials, powers, and/or potential bias, the spatialdistribution of the neutral species, radicals, and electrons in theplasma may be modified in a localized manner, allowing customization ofprocess characteristics, such as smoothing uniformity or locallyenhanced or reduced smoothing rates (e.g., to tailor to differentpattern densities in different parts of a substrate) and so on. Suchmulti-zone control plate 264 maybe sued to active control of the neutralspecies, radicals, and electrons distribution, and thus, allow forenhanced process control. More embodiment of the control plate 264 willbe further discussed above with referenced to FIGS. 7-9.

During substrate processing, gas pressure within the interior of theprocessing chamber 248 may be controlled in a predetermined range. Inone embodiment, the gas pressure within the interior processing region212 of the processing chamber 248 is maintained at about 0.1 to 999mTorr. The substrate 250 may be maintained at a temperature of betweenabout 10 to about 500 degrees Celsius.

Furthermore, the processing chamber 248 may include a translationmechanism 272 configured to translate the support pedestal 214 and thecontrol plate 264 relative to one another. In one embodiment, thetranslation mechanism 272 is coupled to the support pedestal 214 to movethe support pedestal 214 laterally relative to the control plate 264. Inanother embodiment, the translation mechanism 272 is coupled to theplasma generator source 202 plasma generator source 202 and/or thecontrol plate 264 and/or the shield plate 262 to move the plasmagenerator source 202 plasma generator source 202 and/or the controlplate 264 and/or the shield plate 262 laterally relative to the supportpedestal 214. In yet another embodiment, the translation mechanism 272moves one or more of plasma generator source 202, the control plate 264and shield plate 262 laterally relative to the support pedestal 214. Anysuitable translation mechanism may be used, such as a conveyor system,rack and pinion system, an x/y actuator, a robot, electronic motors,pneumatic actuators, hydraulic actuators, or other suitable mechanism.

The translation mechanism 272 may be coupled to a controller 240 tocontrol the scan speed at which the support pedestal 214 and plasmagenerator source 202 and/or the control plate 264 and/or the shieldplate 262 move relative to one another. In addition, translation of thesupport pedestal 214 and the plasma generator source 202 and/or thecontrol plate 264 and/or the shield plate 262 relative to one anothermay be configured to be along a path perpendicular to the predeterminedtrajectory 274 of the neutral species, radicals, or electrons the uppersurface 253 of the substrate 250. In one embodiment, the translationmechanism 272 moves at a constant speed, of approximately 2 millimetersper seconds (mm/s). In another embodiment, the translation of thesupport pedestal 214 and the plasma generator source 202 and/or thecontrol plate 264 and/or the shield plate 262 relative to one anothermay be moved along other paths as desired.

The controller 240, including a central processing unit (CPU) 244, amemory 242, and support circuits 246, is coupled to the variouscomponents of the reactor 200 to facilitate control of the processes ofthe present disclosure. The memory 242 can be any computer-readablemedium, such as random access memory (RAM), read only memory (ROM),floppy disk, hard disk, or any other form of digital storage, local orremote to the reactor 200 or CPU 244. The support circuits 246 arecoupled to the CPU 244 for supporting the CPU 244 in a conventionalmanner. These circuits include cache, power supplies, clock circuits,input/output circuitry and subsystems, and the like. A software routineor a series of program instructions stored in the memory 242, whenexecuted by the CPU 244, causes the reactor 200 to perform a plasmaprocess of the present disclosure.

FIG. 2A only shows one exemplary configuration of a plasma reactor thatcan be used to practice the disclosure. For example, other types ofreactors may utilize different types of plasma power and magnetic powercoupled into the plasma chamber using different coupling mechanisms. Insome applications, different types of plasma may be generated in adifferent chamber from the one in which the substrate is located, e.g.,remote plasma source, and the plasma subsequently guided into thechamber using techniques known in the art.

FIG. 3 depicts an electron trajectory diagram passing through thecontrol plate 264 depicted in FIG. 2 according to one embodiment of thedisclosure. As the filtered neutral species, radicals, and electrons(e.g., electron beam source) passing through the shield plate 262 areaccelerated toward the upper surface 253 of the substrate 250, thefiltered neutral species, radicals, and electrons (e.g., electron beamsource) subsequently passing through the control plate 264 may beconfined to pass through the apertures 268 formed in the control plate264. As the group of electromagnetic coils 221 are disposed around thecontrol plate 264, the neutral species, radicals, and electrons (e.g.,electron beam source) passing therethough may keep orbiting around andtravelling down in the predetermined trajectory 274 confined by theapertures 268 of the control plate 264 and reach to desired regions onthe upper surface 253 of the substrate 250. By utilization of thecontrol plate 264, the trajectory 274 of the neutral species, radicals,and electrons (e.g., electron beam source) may be efficiently controlledin a manner with enhanced electron spinning momentum so as to enableelectrons to travel deep down to the bottom of the structures formed onthe substrate while continuing to spin around the horizontal plane sothat the electrons grind and smooth the roughness from the edge of thestructures formed on the substrate 250.

FIG. 4 illustrates a flow diagram of one embodiment of performing aphotoresist line width roughness (LWR) control process 400 according toone embodiment of the disclosure. The process 400 may be stored inmemory 242 as instructions that executed by the controller 240 to causethe process 400 to be performed in an ICP plasma processing chamber,such as the ICP plasma reactor 200 depicted in FIG. 2A or other suitablereactors.

The process 400 begins at a block 402 by transferring a substrate, suchas the substrate 250 depicted in FIG. 2A, into the processing chamber248 for processing. The substrate 250 may have a target material 512 tobe etched disposed thereon, as shown in FIG. 6, disposed under aphotoresist layer 514. In one embodiment, the target material 512 to beetched using the photoresist line width roughness (LWR) control process400 may be a dielectric layer, a metal layer, a ceramic material, orother suitable material. In one embodiment, the target material 512 tobe etched may be a dielectric material formed as a gate structure or acontact structure or an inter-layer dielectric structure (ILD) utilizedin semiconductor manufacture. Suitable examples of the dielectricmaterial include SiO₂, SiON, SiN, SiC, SiOC, SiOCN, amorphous-carbon(a-C), or the like. In another embodiment, the target material 512 to beetched may be a metal material formed as an inter-metal dielectricstructure (IMD) or other suitable structures. Suitable examples of metallayers include Cu, Al, W, Ni, Cr, or the like.

At block 404, a photoresist line width roughness (LWR) control process400 may be performed on the substrate 250 to grind, modify and trimedges 516 of the photoresist layer 514, as shown in FIG. 5. Thephotoresist line width roughness (LWR) control process 400 is performedproviding a source of electrons. In one embodiment, the electrons areproviding by generating an ICP plasma in the processing chamber 248. TheICP plasma is generated by the plasma generator source 202 disposed inthe processing chamber 248. As discussed above, the plasma as generatedmay include different types of reactive species, such as electrons,charges, ions, neutral species, and so on either with positive ornegative charges. The excited plasma is used to extract electrons whichare moved and accelerated in a circular motion toward the upper surface253 of the substrate 250.

At block 406, as the plasma is advanced toward the substrate surface,the plasma then passes through the shield plate 262 disposed in theprocessing chamber 248. A voltage is applied to the shield plate 262 tocreate a voltage potential, so as to attract ions from the plasma,thereby efficiently filtering ions from the plasma, while allowing onlyneutral species, such as radicals and electrons (e.g., electron beamsource), to pass through the apertures 270 of the shield plate 262 tothe substrate surface. In one embodiment, the voltage is applied to theshield plate 262 from power source 260 between about 50 Volts DC andabout 200 Volts DC.

At block 408, after passing through the shield plate 262, the filteredplasma (e.g., electron beam source) then travels through the controlplate 264. The control plate 264 may confine the filtered plasma passingtherethrough to a predetermined path so as to increase collimation ofthe filtered plasma (e.g., electron beam source) such that the mildreactive species fall on certain regions of the upper surface 253 of thesubstrate 250. The filtered plasma (e.g., electron beam source) isaccelerated to maintain a substantially helical movement circulates bythe magnetic field generated from the group of the electromagnetic coils221 such that the mild reactive species have sufficient momentum tomaintain a spinning motion down to the upper surface 253 of thesubstrate 250. A power supplied to the control plate 264 may generate anelectric field to interact with the magnetic field generated from thegroup of the electromagnetic coils 221 to enhance/maintain the helicalmotion of the mild reactive species such that sufficient momentum andenergy is provided to keep the mild reactive species spinning down tothe upper surface 253 of the substrate 250. The spin electrons may,thus, grind the structures with sufficient momentum all the way tobottoms of the structures formed on the upper surface 253 of thesubstrate 250.

At block 410, the line width roughness (LWR) of the photoresist layer514 may be adjusted, grinded, modified, controlled during theplasma-induced process. As depicted in FIG. 5, the circular movement 504of the electrons may smoothly grind, collide, and polish away the unevenedges 516 of the photoresist layer 514. The process may be continuouslyperformed until a desired degree of roughness, e.g., straightness, (asshown by imaginary line 510) of photoresist layer 514 is achieved. By agood control of the electron momentum, the uneven surfaces andprotrusions from edges 516 of the photoresist layer 514 may be graduallyflattened out, thereby efficiently controlling the photoresist linewidth roughness (LWR) within a desired minimum range. The electronmomentum or neutral species concentration may be controlled by the powergenerated from the interaction between the magnetic field and theelectric field and the gases supplied thereto. In one embodiment, byadjusting the power supplied to generate the plasma power and themagnetic field, different electron momentum or mobility may be obtained.

In one embodiment, the distribution of the electrons and/or neutralspecies (e.g., electron beam source) may be controlled by usingdifferent control plate 264 with different materials or differentcharacteristics. More embodiment of the control plate 264 with differentmaterials or different characteristics will be further discussed abovewith referenced to FIGS. 7-9.

During processing, at block 410, several process parameters may becontrolled to maintain the line width roughness of the photoresist layer514 at a desired range. In one embodiment, the plasma power may besupplied to the processing chamber between about 50 Watt and about 2000Watt. The magnetic field generated in first group of coils or magneticsegments 208 in the processing chamber may be controlled between about500 Gauss (G) and about 1000 G. A DC and/or AC power between about 100watts and about 2000 watt may be used to generate a magnetic field inthe processing chamber. The magnetic field generated in group ofelectromagnetic coils 221 in the processing chamber may be controlledbetween about 100 G and about 200 G. A DC and/or AC power may be appliedto the control plate 264 between about 100 Watt and about 2000 Watt maybe used to generate magnetic field in the processing chamber. Thevoltage between about 50 Volts DC and about 200 Volts DC is applied tothe shield plate 262 to filter the plasma as generated from the plasmagenerator 202. The pressure of the processing chamber may be controlledat between about 0.5 milliTorr and about 500 milliTorr. A processing gasmay be supplied into the processing chamber to assist modifying,trimming, and controlling the edge roughness of the photoresist layer514. As the materials selected for the photoresist layer 514 are oftenorganic materials, an oxygen containing gas may be selected as theprocessing gas to be supplied into the processing chamber to assistgridding and modifying the roughness and profile of the photoresistlayer 514. Suitable examples of the oxygen containing gas include O₂,N₂O, NO₂, O₃, H₂O, CO, CO₂, and the like. Other types of processing gasmay also be supplied into the processing chamber, simultaneously orindividually, to assist modifying the roughness of the photoresist layer514. Suitable examples of the processing gas include N₂, NH₃, Cl₂ orinert gas, such as Ar or He. The processing gas may be supplied into theprocessing chamber at a flow rate between about 10 sccm to about 500sccm, for example, about between about 100 sccm to about 200 sccm. Theprocess may be performed between about 30 second and about 200 second.In one particular embodiment, the O₂ gas is supplied as the processinggas into the processing chamber to react with the photoresist layer 514so as to trim and modify the line width roughness (LWR) of thephotoresist layer 514 disposed on the substrate 250.

The photoresist line width roughness (LWR) control process 400 may becontinuously performed until a desired minimum roughness of thephotoresist layer 514 is achieved. In one embodiment, line widthroughness 513 of the photoresist layer 514 may be controlled in a rangeless than about 3.0 nm, such as between about 1.0 nm and about 1.5 nm.The photoresist line width roughness (LWR) control process 400 may beterminated after reaching an endpoint signaling indicating a desiredroughness of the photoresist layer 514 is achieved. Alternatively, thephotoresist line width roughness (LWR) control process 400 may beterminated by a preset time mode. In one embodiment, the photoresistline width roughness (LWR) control process 400 may be performed forbetween about 100 seconds and between about 500 seconds.

FIG. 6 depicts an exemplary embodiment of a cross sectional view of thephotoresist layer 514 already having the photoresist line widthroughness (LWR) control process 400 performed thereon. After thephotoresist line width roughness (LWR) control process 400, a smoothedge surface is obtained. The roughness of the photoresist layer 514 issmoothed out and trimmed in a manner to minimize the edge roughness andsmooth the edge morphology of the photoresist layer 514. The smooth edgesurface formed in the photoresist layer 514 defines a sharp and welldefined opening 604 in the patterned photoresist layer 514 to expose theunderlying target material 512 for etching, thereby etching a preciseand straight opening width 606 to be formed as a mask layer. In oneembodiment, the width 606 of the openings 604 may be controlled betweenabout 15 nm and about 35 nm.

In one embodiment, the underlying target material 512 may be etched byan etching process performed in the same chamber used to perform theline width roughness (LWR) control process, such as the processingchamber 248 depicted in FIG. 2. In another embodiment, the underlyingtarget material 512 may be etched by an etching process performed in anyother different suitable etching chamber integrated in a cluster systemwhere the line width roughness (LWR) process chamber may be incorporatedthereto. In yet another embodiment, the underlying target material 512may be etched by an etching process performed in any other differentsuitable etching chamber, including stand-alone chamber separated fromthe line width roughness (LWR) process chamber or separated from acluster system where the line width roughness (LWR) process chamber maybe incorporated thereto.

In one embodiment, the gas mixture utilized to perform the line widthroughness (LWR) process is configured to be different from the gasmixture utilized to etch the underlying target material 512. In oneembodiment, the gas mixture utilized to perform the line width roughness(LWR) process includes an oxygen containing gas, such as O₂, and the gasmixture utilized to etch the underlying target material 512 includes ahalogen containing gas, such as fluorine carbon gas, chlorine containinggas, bromide containing gas, fluorine containing gas, and the like.

FIG. 7 depicts one embodiment of a plate 700 having different zones invarious arrangements. In the embodiment depicted in FIG. 7, the plate700 has different zones, 702, 704, 706 arranged in concentric rings. Theplate 700 may be used as one or both of a control plate or shield platein the embodiment of FIG. 2A. The concentric ring configuration, forexample, may be useful in compensating for plasma non-uniformities (in aradial direction) that may arise from non-uniform gas flow patterns inthe chamber.

FIG. 8 depicts another embodiment of a plate 800 having different zonesin various arrangements. The plate 800 may be used as one or both of acontrol plate or shield plate in the embodiment of FIG. 2A. In theembodiment depicted in FIG. 8, the plate 800 is configured to have zonesor segments based on the specific mask patterns in order to achievedifferent smoothing rate resulted on the substrate surface. The plate800 is divided into two zones 802, 804, whose spatial configurationscorrespond to or correlate with respective regions on a mask havingdifferent pattern densities. For example, if zone 802 corresponds to aregion on the mask requiring a relatively high smoothing rate than therest of the mask, zone 802 may be provided with larger diameter ofapertures 806. Alternatively, zones 802, 804 may be made of materialswith different dielectric contacts and/or different potential biases, soas to provide different electron (and/or neutral species) spinning orrotating rate may be contained.

FIG. 9 depicts yet another embodiment of a plate 900 having differentzones in various arrangements. The plate 800 may be used as one or bothof a control plate or shield plate in the embodiment of FIG. 2A. In theembodiment depicted in FIG. 9, the plate 900 is configured to have aplurality of zones or segments 902, 904, 906, 908. At least two zonesare made of different materials compatible with process chemistries. Atleast two zones may be independently biased to maintain a potentialdifference between the biased zones. The use of materials havingdifferent dielectric constants or different potential bias allows usersto tune the plasma characteristics or different rotating speed andmomentum. Additionally, the sizes of apertures 910, 912, 914, 916located in different zones 902, 904, 906, 908 of the plate 900 may bearranged in any combinations or configurations.

Thus, the present disclosure provides methods and an apparatus forcontrolling and modifying line width roughness (LWR) of a photoresistlayer with enhanced electron spinning momentum. The method and apparatuscan advantageously control, modify and trim the profile, line widthroughness and dimension of the photoresist layer disposed on a substrateafter a light exposure process, thereby providing accurate criticaldimension control of an opening in the photoresist layer so thesubsequent etching process may have accurately transfer criticaldimensions to the underlying layer being etched through the opening.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A method for controlling line width roughness ofa photoresist layer disposed on a substrate comprising: providing asubstrate having a patterned photoresist layer disposed thereon into aprocessing chamber; supplying a gas mixture into the processing chamber;generating an electron beam from the gas mixture having electrons movingin a circular mode from the gas mixture; generating a magnetic field toenhance spinning of electrons in the electron beam moving in thecircular mode to a substrate surface; filtering ions from the electronbeam by passing the ions through a plate, wherein the plate has at leasttwo zones having different dielectric constants or different potentialbias; and trimming an edge profile of the patterned photoresist layerdisposed on the substrate surface with the enhanced electrons.
 2. Themethod of claim 1, further comprising: directing the filtered electronsthrough the magnetic field.
 3. The method of claim 1, wherein generatingthe magnetic field further comprising: applying a DC or AC power to oneor more electromagnetic coils disposed around an outer circumference ofthe processing chamber.
 4. The method of claim 1, wherein the gasmixture comprises an oxygen containing gas.
 5. A method for controllingline width roughness of a photoresist layer disposed on a substratecomprising: supplying a gas mixture into a processing chamber having asubstrate disposed therein, wherein the substrate has a patternedphotoresist layer disposed thereon; generating an electron beam in theprocessing chamber from the gas mixture supplied in the processingchamber; applying a voltage to a shield plate disposed in the processingchamber to filter ions from the electron beam; directing the electronbeam through a control plate; filtering ions from the electron beam bygassing the ions through the control plate, wherein the control platehas at least two zones having different dielectric constants ordifferent potential bias; applying a DC or AC power to a group of one ormore electromagnetic coils disposed around an outer circumference of theprocessing chamber to generate a magnetic field; enhancing movement ofthe electron beam in circular mode by passing through the filteredelectron beam in the magnetic field; and rotating the electron beam totrim an edge profile of the patterned photoresist layer using theelectron beam.
 6. The method of claim 5, wherein directing the electronbeam further comprises: applying a power to the control plate.
 7. Themethod of claim 5, wherein supplying the gas mixture further comprises:supplying an oxygen containing gas into the processing chamber.
 8. Themethod of claim 5, wherein the filtered electron beam include neutralradicals and electrons.